Ignition coils are components that use the coupling between a primary winding and a secondary winding to transform relatively low voltages from the battery into high voltages that are supplied to the spark plugs in vehicle gasoline engines. The spark plugs start the internal combustion process that drives the rods and hence, crankshaft and axles. In older systems, a single ignition coil is provided, and a distributor sends the pulses from the coil through respective high voltage spark plug wires to the spark plugs in the cylinders in accordance with a timing that is established by the distributor.
In relatively modern engines, an engine can have several ignition coils, one for each cylinder or for each pair of cylinders, thereby advantageously eliminating the need for distributors and high voltage wires and also providing more precise control of the engine timing. One example of such an ignition coil system is set forth in U.S. Pat. No. 6,556,118, owned by the present assignee and incorporated herein by reference.
Ignition coils have been made in a so-called “plug top coil” (PTC) configuration in which the coil is mounted above the spark plug well. As recognized herein, it is sometimes required that the axis of the coil be centered over the plug well, requiring in turn the high voltage to be routed around a pole piece of the primary coil core. The high voltage wire typically is protected from the pole piece by a separate plastic component that also is designed to reduce the strain between epoxy encapsulate in the coil assembly and the pole piece.